Fuse cartridge devices with auxiliary contact

ABSTRACT

The cartridge fuse has a radially movable striker pin disposed in a peripheral chamber of the cartridge body, the cartridge being associated with an auxiliary contact mechanism disposed in front of the striker pin so as to be actuated thereby. In order to avoid, when the cartridge blows, the highly ionized hot gases which issue radially from the space between the striker pin and the wall of its housing chamber from blowing laterally between the periphery of the cartridge body and the contact mechanism, upon contact with the contact mechanism and thereafter flowing laterally towards the cartridge heads, a seal is provided between the mechanism or its support and the cartridge body. The gases expand in the space deliminted by the seal and they leak through the mechanism and/or the support to reach the ambient atmosphere in a cooled and disionized state.

United States Patent l i 1 i 1 W Inventor Lucien Ferraz Lyon, France Appl. No. 784,02! Filed Dec. 16, I968 Patented July l3, l97l Assignee Societe Lucien Fcrraz & Cie

Lyon, France Priority Dec. 26, i967 France 49,466

FUSE CARTRIDGE DEVICES WITH AUXILIARY CONTACT FOREIGN PATENTS |,0O7,4l7 l0] I965 Great Britain Primary Examine'r- Bernard A. Gilheany Assistant Examiner-Dewitt M. Morgan Attorney-Alexander 8t Dowell ABSTRACT: The cartridge fuse has a radially movable striker pin disposed in a peripheral chamber of the cartridge body, the cartridge being associated with an auxiliary contact mechanism disposed in front of the striker pin so as to be actuated thereby. In order to avoid, when the cartridge blows, the highly ionized hot gases which issue radially from the space between the striker pin and the wall of its housing chamber from blowing laterally between the periphery of the cartridge body and the contact mechanism, upon contact with the contact mechanism and thereafter flowing laterally towards the cartridge heads, a seal is provided between the mechanism or its support and the cartridge body. The gases expand in the space deliminted by the seal and they leak through the mechanism and/or the support to reach the ambient atmosphere in a cooled and disionized state.

FUSE CARTRIDGE DEVICES WITH AUXILIARY CONTACT The present invention relates to fuse cartridge devices of the kind comprising an auxiliary contact mechanism mounted in a support removably secured to the cartridge in front of the striker pin of the pin of the latter so as to be actuated by the said pin when the cartridge blows.

A problem in such devices is that when the inner fusible elements or links of the cartridge begin to melt, there appears an are which generates highly ionized gases or flames under a considerable pressure. These gases flow through all the available passages and more particularly between the striker pin and the wall of the chamber in which it is slidably disposed. When the device comprises an auxiliary contact mechanism mounted in front of the striker pin, the gases are deviated along the periphery of the body of the cartridge towards the metallic heads thereof and if the voltage across the cartridge is high, an arc may be struck between these heads.

British specification No. 1,007,4[7 describes a fuse cartridge device wherein the auxiliary contact mechanism is incorporated in a gastight cartridge or is secured thereto in a wholly gastight manner. This is of course a marked advantage in various cases, as for instance in a damp or aggressive atmosphere. But such a solution requires a particular and relatively expensive construction of the cartridge and besides an almost perfect gastightness may in some instances be considered as a disadvantage since it does not limit the building up of the internal pressure within the cartridge body which may burst.

In accordance with the present invention in a fuse cartridge device of the kind above referred to a seal is interposed between the support and the outer periphery of the cartridge body so as to prevent the highly ionized hot gases issuing from the cartridge through the chamber in which the striker pin is mounted, from flowing laterally along the cartridge body, the said gases thus being compelled to expand in the space defined by the cartridge body, the support, the auxiliary contact mechanism and the seal, and to leak outwardly through the narrow passages existing in the auxiliary contact mechanism and/or in its support, whereby they reach the outer atmosphere in the deionized and cooled state.

In the accompanying drawings:

FIG. I is a fragmental section ofa first embodiment ofa fuse cartridge device according to the present invention.

FIG. 2 illustrates a modification.

In FIG. I reference numeral 1 designates the tubular body of a conventional fuse cartridge, this body being made of any appropriate heat-resistant insulating material. The inner crossscctional contour of body I is preferably circular, while its outer one may be either circular or square. Each end of body I is closed by a flat metallic head 2 united with an appropriate outer contact device, such as a blade 3, and the inner side of each head 2 is formed with a cylindrical boss 4 on the periphery of which the corresponding ends of the fusible elements or links 5 ofthe cartridge are soldered, these links being embedded in a pulverulent mass 6 of an appropriate arc quenching material, as for instance quartz sand. The heads 2 are secured to the ends of the tubular body I by means of Iongitudinal screws 7. A sealing gasket may be interposed between each head 2 and body I, il'dcsired.

An auxiliary fusible wire 8 has its ends clamped between each head 2 and the adjacent end of body I, so as to connect heads 2 electrically with each other in parallel with the fusible links 5. The central portion of this wire 8 is passed through two radial perforations In of small diameter provided in the wall of body 1 and which open in a cylindrical chamber lb. A striker pin 9 is freely slidable within this chamber lb. The striker pin 9 is in the form of an inverted cup-shaped member and its upper wall has two holes 90 through which wire 8 is passed so as to retain the said pin against the action of a compression spring I disposed in the bottom of chamber lb. The striker pin is preferably provided with an insulating cap II which covers the portion of wire 8 comprised between holes 90. I

A L-shaped member 12 has its vertical branch secured against the outer side of each head 2, conveniently by means of at least one of the above-mentioned screws 7, in the manner illustrated. The horizontal branches of members 12 are directed towards each other and they receive screws 13 passed through lateral portions of an insulating support I4 in which is frictionally retained a microswitch or auxiliary contact mechanism 15 whose actuating button 16 is situated in front of the striker pin 9 of the cartridge.

The side of support 14 which faces the cartridge body 1 isformed with a groove 14:: in which is secured the base of a seal 17 as for instance of silicone rubber. This seal is applied against the outer periphery of the canridge body 1.

When the fusible links 5 melt the auxiliary wire 8 is submitted to the full voltage which appears across the cartridge and it is almost immediately volatilized. The striker pin 9 is thus liberated and under the action of its spring I0 it actuates the button [6 of the microswitch IS. The highly ionized hot gases or flames resulting from the electric are which appears during a short time through the break formed in the fusible links 5 when they begin to melt, may leak through holes Ia and through the annular clearance provided between pin 9 and the wall of chamber 1b. They thus reach the space defined by the periphery of body I, by the undersides of support 14 and of microswitch l5, and by seal I7. They expand in this space while being prevented from flowing outwardly along the periphery of body 1 towards heads 2. Since microswitch I5 is not retained in support 14 in a perfectly gastight manner, and is not itself perfectly gastight, these gases may leak outwardly between or through the said parts as through a labyrinth seal. They finally reach the outer atmosphere in a deionized and cooled state. Any arcing between heads 2 or L-shaped members 12 due to the presence of ionized gases is thus fully avoided.

Under normal conditions seal 17 prevents penetration of dust and moisture into the cartridge.

In the embodiment of FIG. 2 the seal 17 is carried by a ring I8 which is slidably mounted in an annular slot 14b of support 14 and which is urged outwardly by a spring I9 disposed in the bottom of the slot.

Ring 18 and slot I4b may be circular, rectangular or square, as desired. With such an arrangement seal I7 is always regularly applied against the outer periphery of the insulating body I of the cartridge in spite of manufacturing tolerances. It will be noted that rings I8 is not mounted in slot 14b in a perfectly gastight manner and that here also the hot gases may leak outwardly, but they have to flow through quite narrow passages and to pass through the bottom ofslot l4b, which acts as an intermediate expanding chamber, the whole again forming a labyrinth seal due to which the said gases are cooled and deionized.

it is obvious that in both embodiments the L-shaped members 12 could be formed integral with heads 2. Also in lieu ofa microswitch proper with its own casing, as illustrated, the auxiliary contact mechanism could be formed of appropriate parts directly carried by support I4 itself.

The ring I8 may be retained by an abutment such as 20.

I claim:

I. A fuse cartridge device comprising a tubular body of insulating material having two open ends, said body being formed with a laterally opening chamber; a pair of terminal heads each at one end of said tubular body to close same; fuse link means interconnecting said terminal heads within said tubular body; a striker pin slidably disposed in said chamber of said tubular body; spring means urging said striker pin outwardly of said tubular body; restraining means having ends respectively secured to said ends of said tubular body and each electrically connected with one of said terminal heads, said restraining means being attached to said striker pin to retain same within said chamber of said body against the ac tion of said spring means and said restraining means being destructed to liberate said striker pin when said fuse link means melt under the action ofa heavy current; auxiliary contact means disposed in front of said striker pin to be actuated by same when liberated; supporting means disposed laterally of said tubular body to support said auxiliary contact means; means to secure said supporting means to said tubular body in spaced relation; and sealing means interposed between said supporting means and said tubular body around said striker pin to prevent highly ionized hot gases issuing radially from said body around said striker pin to flow laterally along said body towards said terminal heads.

2. In a fuse cartridge device as claimed in claim 1, said auxiliary contact means, said supporting means, said sealing means and said tubular body defining a space for expansion of said gases to deionize and cool same.

3. In a fuse cartridge device as claimed in claim 2, said supporting means and said auxiliary contact means being fonned with narrow passages through which said gases may leak.

4. In a fuse cartridge device as claimed in claim I, said sealing means being carried by a ring movable with respect to said supporting means, said supporting means including a slot to slidably receive said ring, and said ring being urged towards said tubular body by spring means disposed within said slot.

5. In a fuse cartridge as claimed in claim 1, said supporting means being in the form of an insulating block and said means to secure said block to said tubular body being formed of two L-shaped metallic members with one of the branches of each of same being maintained against one of said terminal beads by at least one screw screwed into said tubular body through said one of said terminal heads to clamp same against one end of said tubular body.

6. In a fuse cartridge as claimed in claim I, said supporting means being in the form of a block having an open-ended passage disposed substantially radially to said tubular body, and said auxiliary contact means being formed of a microswitch fitting in said passage in a nonperfectly gastight manner, said microswitch having an actuating button disposed in front of said striker pin to be pushed by same. 

1. A fuse cartridge device comprising a tubular body of insulating material having two open ends, said body being formed with a laterally opening chamber; a pair of terminal heads each at one end of said tubular body to close same; fuse link means interconnecting said terminal heads within said tubular body; a striker pin slidably disposed in said chamber of said tubular body; spring means urging said striker pin outwardly of said tubular body; restraining means having ends respectively secured to said ends of said tubular body and each electrically connected with one of said terminal heads, said restraining means being attached to said striker pin to retain same within said chamber of said body against the action of said spring means and said restraining means being destructed to liberate said striker pin when said fuse link means melt under the action of a heavy current; auxiliary contact means disposed in front of said striker pin to be actuated by same when liberated; supporting means disposed laterally of said tubular body to support said auxiliary contact means; means to secure said supporting means to said tubular body in spaced relation; and sealing means interposed between said supporting means and said tubular body around said striker pin to prevent highly ionized hot gases issuing radially from said body around said striker pin to flow laterally along said body towards said terminal heads.
 2. In a fuse cartridge device as claimed in claim 1, said auxiliary contact means, said supporting means, said sealing means and said tubular body defining a space for expansion of said gases to deionize and cool same.
 3. In a fuse cartridge device as claimed in claim 2, said supporting means and said auxiliary contact means being formed with narrow passages through which said gases may leak.
 4. In a fuse cartridge device as claimed in claim 1, said sealing means being carried by a ring movable with respect to said supporting means, said supporting means including a slot to slidably receive said ring, and said ring being urged towards said tubular body by spring means disposed within said slot.
 5. In a fuse cartridge as claimed in claim 1, said supporting means being in the form of an insulating block and said means to secure said block to said tubular body being formed of two L-shaped metallic members with one of the branches of each of same being maintained against one of said terminal heads by at least one screw screwed into said tubular body through said one of said terminal heads to clamp same against one end of said tubular body.
 6. In a fuse cartridge as claimed in claim 1, said supporting means being in the form of a block having an open-ended passage disposed substantially radially to said tubular body, and said auxiliary contact means being formed of a microswitch fitting in said passage in a nonperfectly gastight manner, said microswitch having an actuating button disposed in front of said striker pin to be pushed by same. 